14 CLINICAL STUDIES
14.1 Management of Postherpetic Neuralgia (Study PHN CR)
Support for efficacy of LYRICA CR for the management of PHN and diabetic peripheral neuropathy (DPN) was based on the efficacy of LYRICA for these indications along with an adequate and well-controlled study in adults with PHN. This 19-week randomized withdrawal study compared daily doses of LYRICA CR 82.5 mg, 165 mg, 247.5 mg, 330 mg, 495 mg, or 660 mg with placebo. Those enrolled were required to have pain present for more than 3 months after healing of the herpes zoster skin rash and a baseline pain score of greater than or equal to 4 on the numeric rating scale (NRS)-Pain (assessed over a 1 week recall period). The baseline mean pain scores were 6.83 for LYRICA CR-treated patients vs. 6.85 for placebo-treated patients. A total of 82.4% of patients completed the single-blind phase of the study. Patients were considered responders if they had at least a 50% reduction in pain in the single-blind phase. Those who responded to treatment were then randomized in the double-blind phase to treatment with either the LYRICA CR dose achieved in the single-blind phase or placebo. Patients were treated for up to 3 months following randomization. A total of 87.5% of LYRICA CR-treated patients and 78% of placebo-treated patients completed the double-blind phase of the study.
LYRICA CR treatment demonstrated statistically significant improvement in the endpoint change in mean pain score from baseline compared to placebo. For a range of levels of improvement in pain intensity from baseline to study endpoint, Figure 1 shows the fraction of patients achieving that degree of improvement. The figure is cumulative, so that patients whose change from baseline is, for example, 50%, are also included at every level of improvement below 50%. Patients who did not complete the study were assigned 0% improvement. In the LYRICA CR group, 79.8% of subjects achieved at least a 30% improvement and 73.6% at least 50% improvement in pain intensity. In the placebo group, 64.9% of subjects achieved at least a 30% improvement and 54.6% at least a 50% improvement in pain intensity.
Figure 1. Percent of Patients Achieving Various Levels of Improvement in Pain Intensity (N=413)
14.2 Management of Fibromyalgia (Study FM CR)
A double-blind, placebo-controlled, randomized withdrawal trial of LYRICA CR in adults with fibromyalgia failed to demonstrate efficacy.